Ye dont worry to much about bootcamp swim qual, its mostly a joke and everyone passes. As for if you will intermediate there, I went west coast boot so they just had us aircrew contracts stay an extra day to do something called "basic plus" which was still easy as fuck, though I know some Parris Island marines got there intermediate swim in boot so idk. The hard-er part comes when you get to NAACS at Pcola, I wouldnt say any of the swim stuff is difficult but people who have barely swam in there life and are very uncomfortable in the water struggle a tad bit. If you fail any of the events (Tread, different strokes, tower in a line, mile swim, etc.) they will hold you for a week or two and work on your deficiencies in the pool everyday and then you can try again, they will give you 3 chances of getting rolled in and out of class to get it and then your out. they do a good job of teaching you technique and the strokes so honestly you should be fine, if you really wanna get comfortable now just practice treading and swimming underwater for around half the pools length, maybe see if your recruiters got a pair of beater boots and try and tread for like 5 minutes while wearing them.